- A rise in religious suicide bombing,
sending souls to heaventargeted at scientists bringing forth the singularity
- Decline in religious observance - rise in atheism
- Rise in religions prohibiting life-saving treatments
But switching slightly towards predictions of the Rapture - that's low real-life cost, and relatively low belief cost. Just model folks, as Caplan does, as optimizing over the psychic cost of diverging from a bliss belief and the real-world cost of holding any beliefs, and the comparative statics on this one seem pretty obvious.
Update: LemmusLemmus makes the obvious point on cohort changes over time leading to more atheism: he's certainly right. Fewer will opt into religion when fear of death is gone. And Adam notes that terrorism targeted at the scientists bringing forth life extension is plausible. I'd agree - there could be a few folks nuts enough to do it.